1. Field of the Invention
The invention is directed to devices and methods for adjusting the contact between two rollers of a printing mechanism of a rotary printing press which are adjustable with respect to their distance relative to one another.
2. Discussion of the Prior Art
In inking and dampening mechanisms in rotary printing presses, there are a great many rollers which are adjustable with respect to their distance from adjacent rollers. For example, such rollers are the inking rollers or dampening rollers which are adjusted in a determined manner to contact the form cylinder and friction cylinders.
For this purpose, it is known to effect the adjustment based upon the printing width. Yellow ink is applied to both sides of the rollers and distributed by executing a number of revolutions. The printing mechanism is then stopped for roughly 15 seconds. When the rotation of the rollers is resumed subsequently, the printing width is shown by two marks. This process is repeated for different roller adjustments until the two marks are parallel and at a desired distance from one another. This adjustment procedure is time-consuming and, due to the large number of adjustments to be made in a printing press, adds enormously to the cost of the printed material.
Furthermore, a device is known by which the rollers can be adjusted via the contact pressure. For this purpose, flexible tongues are inserted in the roller gap one after the other on both sides of the rollers. However, these tongues may not be bent during the measuring process, since this would result in incorrect measurements. This condition cannot be met in most measurement locations due to the narrow construction of the inking mechanism and the dampening mechanism.
It is also known to adjust the distance between rollers proceeding from a contacting position. Values for an optimal adjustment are determined, for example, according to a formula given in B ottcher, Gudehus, T., The Optimal Adjustment of Printing Rollers, Formula (10), offprint from printing of 5/1985, 6/1985 and 9/1986, Felix B ottcher GmbH & Co., Cologne, 1984.
A device for determining the contacting position of two rollers is shown in DE 42 03 940 A1. In this device two rollers are advanced toward one another until an elastic element is elastically deformed. Corresponding elastic elements are arranged in the bearings of one of the rollers and are deformed during a movement of the bearing pins allowed by play in the bearing as the outer surfaces of the rollers come together. This device is expensive due to the special construction of the roller bearings. Furthermore, the bearing play required for its operation is disadvantageous for the running characteristics of the rollers.